Bending device for an endoscope

ABSTRACT

A bending device for an endoscope operates the bendable portion on the front end side of the insertable portion of the endoscope to bend by moving back and forth an operating wire which is inserted in a coil sheath housed within the insertable portion to connect the bendable portion and an operation portion for bending on the rear end side of the endoscope. The bending device prevents a relative looseness between the coil sheath and the operating wire by fixing the coil sheath at its end on the bendable portion side so as not to rotate around its axis and controlling rotation of the coil sheath at the other end on the operating portion side around the axis thereof within a limit.

This is a divisional of application Ser. No. 168,264, filed Mar. 15,1988 now U.S. Pat. No. 4,841,950, issued on June 27, 1989.

BACKGROUND OF THE INVENTION

The present invention relates to a bending device for an endoscope whichprovides a bending operation for a bendable portion of the endoscope bymoving back and forth an operating wire.

In general, medical endoscopes for observing and treating a coelom suchas the stomach and intestines and industrial endoscopes for observingthe inside of a tube such as used in a boiler and a chemical plantrequire to have a bendable function to direct the distal end of theinsertable portion thereof to a desired direction.

To this end, such endoscope is provided with a bending device in which aguide sheath for operating wires comprising a pair of coil sheaths whichare flexible but do not lengthen or shorten in theaxial direction isinserted into the insertable portion of the endoscope and operatingwires are respectively inserted into the pair of coil sheaths so as toprovide the bending operation to the bendable portion of the endoscopeby moving back and forth the operating wires. Specifically, the coilsheath, which generally employs a closely wound coil, has a structure inwhich one end of the operating wire inserted in the closely wound coilis fixed to the distal end of the bendable portion and the other endthereof is connected to a bending operation portion which is provided inthe operation portion of the endoscope so that the bending operation canbe performed by moving back and forth the operating wires at the bendingoperation portion. With this structure, however, looseness would becaused between the coil sheath and the operating wire during the bendingoperation, which is caused by shrinkage of a bendable tube of thebendable portion and the coil sheath and elongation of the operatingwire and the like.

In the case where the bending operation is performed by pulling thestrained operating wire as described above, a compressive force isapplied to a closely wound coil which forms the coil sheath.

The compressive force is twisted in a direction in which the closelywound coil is running down to act so as to axially shorten its length.Accordingly, when the bending operation is repeated, the closely coiledwinding is reduced in length in its axial direction to cause loosenessin the operating wire.

Such looseness involves a play which causes a phenomenon in which nobending is operated until the looseness is canceled, even when anoperating lever or the like is moved, and reduction in a bending angleby a value initially being loosened to lower the insertability and theperformance of observation and treatment of the endoscope.

A technique of canceling looseness is proposed, for example, in JapaneseUtility Model Publication Sho59-31202.

In the proposed technique, a screw member is interposed in a part of anoperating wire so as to change threadably engaging position of the screwmember, thereby a distance between connecting portions of the screwmember being changed by the screwing operation to adjust a length of theoperating wire to cancel looseness.

In such technique, however, repairs and adjustments should be madewhenever looseness is caused. Such correcting operation has to beconducted by a specialist, so that it interrupts the use of an endoscopeand also is very expensive.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a bending device foran endoscope to reliably remove at least shrinkage of a coil sheath,which is one of the causes such as shrinkage of a bendable tube whichforms the bendable portion and a coil sheath which forms a guide sheathand elongation of an operating wire for a relative looseness between thecoil sheath and the operating wire in use for a long time.

According to the present invention, a bending device for an endoscopehas no relative looseness between the coil sheath and the operating wiredue to shrinkage of the coil sheath because the end portion of the coilsheath on the bendable portion side is fixed so as not to rotate aroundits axis and the other end portion thereof on the operation portion sideis controlled in rotation around its axis with a limit (including afixed condition).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 and 2 show a first embodiment of a bending device for anendoscope according to the present invention, FIG. 1 being an explodedperspective view showing a fixing structure of a guide sheath on anoperation portion side which is an essential part of the bending deviceand FIG. 2 being a schematic side view showing the bending device havingthe fixing structure shown in FIG. 1 together with an endoscope;

FIG. 3 is an exploded perspective view showing a second embodiment of abending device for an endoscope according to the present invention;

FIG. 4 is an exploded perspective view showing essential parts of athird embodiment of a bending device for an endoscope according to thepresent invention;

FIG. 5 is an exploded perspective view showing essential parts of afourth embodiment of a bending device for an endoscope according to thepresent invention;

FIG. 6 is an exploded perspective view showing essential parts of afifth embodiment of a bending device for an endoscope according to thepresent invention;

FIG. 7 is a section view showing essential parts of a sixth embodimentof a bending device for an endoscope according to the present invention;

FIGS. 8 to 10 show a seventh embodiment of a bending device for anendoscope according to the present invention, FIG. 8 being an explodedperspective view showing essential parts thereof, FIG. 9 being anenlarged front view showing essential parts thereof and FIG. 10 being anexplanatory view showing movement of the essential parts;

FIGS. 11 and 12 show an eighth embodiment of a bending device for anendoscope according to the present invention; FIG. 11 being an explodedperspective view showing essential parts thereof and FIG. 12 being anexplanatory view showing movement of the essential parts.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1 and 2 show a first embodiment of a bending device according tothe present invention. Particularly, FIG. 2 schematically shows anendoscope such as a fiberscope and an electronic scope on the wholetogether with a bending device of the present invention. An operationportion 1 includes a pair of pulleys 2 (only one is shown in FIG. 2). Apair of operating levers 2a are respectively connected to the pair ofpulleys 2, which constitute a bending operation portion together withthe pulleys 2 so as to rotate the pulleys 2 around their center axis byrotating the operating levers 2a (only one is shown in FIG. 2).

On the other hand, an insertable portion 3 is formed, as is well known,by serially connecting a bendable portion 5 which is formed by rotatablyconnecting a plurality of articulated tube 5a arranged in seriesrelationship one by one with rivets 5b and a distal end body 6 to aflexible tube 4. The insertable portion 3 is connected to the operationportion 1 to form an endoscope body.

A guide sheath 7 which guides operating wires 8 is formed by two pairsof closely wound coils (only a pair of coils are shown in FIG. 2) whichare symmetrically inserted in the flexible tube 4 towards the inner wallthereof and into which the operating wires are respectively inserted.

The operating wires 8 which are wound on the respective pulleys 2 havetheir distal ends fixed to the distal end body 6 after being slidablyinserted into the respective closely wound coils, so that the bendableportion 5 can be longitudinally and transversely bent by pulling theoperating wires 8 with the operating lever 2a rotating. The portion ofthe operating wire which is wound on the pulley 2 is secured to thepulley 2.

The present invention is applied to the fixation of the rear (proximal)ends of the coil sheaths 7 of the structure just described above.

The opposite ends of the coil sheath 7 comprising a closely wound coilare fixed as follows. The front (distal) end of the coil sheath 7 on thebendable portion 5 side is fixed to the inner periphery of a mouthpiece4a at the rear end of the bendable portion by brazing so that the frontend of the coil sheath 7 can not rotate in a twisting direction. Thefixation not to rotate around the axis of the coil sheath 7 may becarried out by soldering, adhesion or the like other than brazing.

The rear end of the coil sheath 7 on the operation portion 1 side isfixed, as shown in FIG. 1 in detail, to a stationary base plate 1a whichconstitutes the operation portion 1 with a fixing member.

Namely, as a fixing member a coil lock member 10 is employed which is ina substantially cylindrical form and has a through-hole of a diameternearly equal to that of a closely wound coil of the coil sheath 7 on thecentral axis thereof. The coil lock member 10 is fixed to the rear endof each of the coil sheaths 7 on the operation portion 1 ide as bybrazing.

A plurality of the operating wires 8 are inserted through thethrough-hole of the coil lock member 10. In addition, a pair of cutportions 11 are provided in the middle of the outer periphery of thecoil lock member 10 so as to have respective planes in parallel to eachother at symmetrical positions shifted by 180° each other.

A coil lock holder 12 is provided uprightly on the base plate 1a on theflexible tube 4 side so as to substantially perpendicularly cross withthe direction of inserting the operating wires 8 through the coilsheaths 7 and is fixed to the base plate 1a with set screws 15. Theholder 12 is made of a plate of the substantially same thickness as awidth of the cut portion of the coil lock member 10. In addition, theholder 12 is provided with upper and lower slits 13 parallel to theplane of the base plate 1a on the transversely opposite sides of thebase plate 1a and extending sideward from the position of the base plate1a where the operating wire 8 is inserted. A width of the slits 13 isdefined to the substantially same as a width between both cut portions11, 11 so that the cut portions 11, 11 of the coil lock member 12 can beinserted into the slits 13 as shown in FIG. 1, resulting in that theslits 13 and the cut portions 11 are engaged together. Thereby, it ispossible to fix the coil lock member 12 so as not to move and rotate it.In addition, a screw 14 for preventing the coil lock member 10 fromescaping sideward is inserted on the transversely opposite sides of theholder 12 such that it passes through the holder 12 on the opening sidesof the upper and lower slits 13, 13 so as not to slip off from theholder 12.

With the first embodiment of the above structure, when the operatinglever 2a is rotated the operating wires 8 are moved back and forththrough the pulleys 2 to bend the bendable portion 5 transversely and/orlongitudinally.

When such bending operation is repeated, a compressive force caused inthe coil sheath 7 works as an action of rotating in a direction ofrunning down the closely wound coiled of the coil sheath 7 to unwind it,so that an axial length of the coil sheath 7 may be reduced because ofreduction in the total number of pitches. In the first embodiment,however, since the front and rear ends of the operating wire 8 arerespectively fixed by brazing and the engagement between the coil lockmember 10 and coil lock holder 12, there is no rotation of the coilsheath 7 around its axis during the bending operation.

Accordingly, no relative distortion involves between the coil endportions on the bendable and operating portion sides, so that the totallength of the coil sheath 7 is not reduced due to reduction of the totalnumber of pitches as seen in the prior art device. As a result, evenwhen an endoscope is used for a prolonged time, no relative lossenessdue to shrinkage of the coil sheath is caused between the coil sheath 7and the operating wire 8.

Consequently, a play and reduction in a bending angle which are thecauses for losseness are practically insignificant, so that it ispossible to maintain good insertability and performance of observationand treatment of an endoscope for a prolonged time.

In addition, since there is no looseness, there is no possibility thatthe use of an endoscope is interrupted and the cost of repairing isreduced.

Other embodiments of the present invention will be described hereinafterwith reference to FIGS. 3 to 12, wherein like reference charactersdesignate like or corresponding parts throughout and their descriptionwill be omitted.

In FIG. 3, which shows a second embodiment of the present invention, twovertical slits 13A are provided on a coil lock holder 12A so that twocoil lock members 10 are inserted into the respective slits 13A.

The structure just described above has advantages that the coil lockholder 12A can be easily manufactured since the number of slits 13A isreduced and also the number of the screws 14 for preventing the coillock member 10 from escaping can be reduced.

In FIG. 4, which shows a third embodiment of the present invention whichis an example of modification of the second embodiment, a coil lockmember 10A is fixed so as not to rotate around its axis by using screws.

Specifically, a plurality of cone shaped holes 20 are circumferentiallyprovided on the middle of the outer periphery of the cylindrical coillock member 10A and screw holes 21 are provided on the transverselyouter sides of the coil lock holder 12A at positions corresponding tothe respective holes 20 of the coil lock members 10A inserted in theslits 13A in place. With such structure, after the coil lock member 10Ais inserted in the slit 13A in place, a set screw 22 is screwed throughthe screw hole 21 to press a conical end 22a of the screw 22 against thehole 20, thereby the coil lock member 10A being fixed.

In FIG. 5, which shows a fourth embodiment of the present invention,through-holes 23 having a diameter substantially equal to that of acylindrical coil lock member 10B are provided on a coil lock holder 12B.The coil lock member 10B is inserted into the through-hole 23 to fix itby brazing, soldering or adhesion so that the coil lock member 10B doesnot rotate around its axis.

With the structure described above, since the coil lock holder 12B willdo as long as only the through-hole 23 is provided thereon and the coillock member 10B will do for use in a cylindrical form and need not toprovide any working, both members can be easily manufactured.

In addition, since the coil lock member 10B can be fixed any positionaround its axis to the coil lock holder 12B, it is easily assembled.

In FIG. 6, which shows a fifth embodiment of the present invention, acoil lock member 10C which is formed in a substantially rectangularparallelepiped has two through-holes 9 of a diameter nearly equal tothat of a closely wound coil of the coil sheath 7 and grooves 18 on theinner side thereof which fit in horizontal slits 13B provided on theopposite sides of a coil lock holder 12C.

The coil lock member 10C is fixed, after the groove 18 is fit in theslit 13B, to the coil lock holder 12C by a screw 14. With thisstructure, it is also possible to fix the coil sheath 7 so as not torotate around its axis.

In FIG. 7, which shows a sixth embodiment of the present invention, thecoil sheath 7 comprising a closely wound coil is fixed to the innerperiphery of the insertable portion 3, that is, the inner periphery of aflex 24 comprising a helical tube of the flexible tube 4 which comprisesthe flex 24, a blade 25 comprising a netted tube and a housing 26, at aplurality of positions of a given interval over the substantiallyoverall length of the closely wound coil by brazing, soldering, adhesionor the like.

In FIG. 8 to 10, which shows a seventh embodiment of the presentinvention, a coil lock member 30 has a through-hole of a diameter nearlyequal to that of a closely wound coil forming the coil sheath 7 on thecentral axis thereof, and is formed of a large diameter portion 33 atthe rear end thereof, a small diameter portion 31 in the middle thereofand a substantially rectangular parallelpiped portion 32 at the frontend thereof. The coil lock member 30 is fixed at the rear end of thecoil sheath 7 on the operation portion 1 side as by soldering. Theoperating wire 8 is inserted into and fixed to the inside of the coillock member 30. A coil lock holder 12D is provided with upper and lowerslits 13C formed in parallel with the base plate 1a of the operationportion 1 on the transversely opposite sides thereof. The small diameterportion 31 is rotatably inserted in the slit 13C. The coil lock holder12D is fixed by a screw 1c at the center portion thereof to a holderfixing member 1b which has a plane perpendicular to the base plate 1aand is fixed to the latter. In addition, a member 34 is fixed to thecoil lock holder 12D in abutment with the coil lock member 30 front theopening side of the slits 13C such that the coil lock member 30 does notslip off on the slit 13C. In this embodiment, the portion 32 of the coillock member 30 forms an anti-rotation portion 35 in the side cornerthereof, as shown in FIG. 9. When the portion 32 whose sectionperpendicular to the axis thereof is square, for example, a side lengtha of the square is taken to meet the following, ##EQU1## where lrepresents a distance between the center axes of slits 13C.

With the structure described above, even when the closely wound coil ofthe coil sheath 7 is going to rotate in a direction of its running down,the anti-rotation portion 35 strikes against another coil lock member30, as shown in FIG. 10, so that the rotation can be controlled within agiven value. In this case, the maximum rotation angle is less than 90°.

Namely, there is little relative distortion between coils on thebendable portion 5 and operation portion 1 sides, so that there is nopossibility that the overall length of the coil sheath 7 is so reduceddue to reduction of the total number of pitches that it exerts a greatinfluence on a play and reduction in a bending angle as seen in thepast.

In FIGS. 11 and 12, which show an eighth embodiment of the presentinvention, a coil lock member 40 is in a substantially cylindrical formand has a small diameter portion 41 and large diameter portions 42 atopposite ends thereof. An anti-rotation pin 43 radially extends from theperiphery of the large diameter portion 42. The small diameter portion41 is rotatably inserted in a slit 13D of a coil lock holder 12E.

With this structure, the rotation of the closely wound coil of the coilsheath 7 can be controlled within a limited value by the anti-rotationpin 43 since, as shown in FIG. 12, the pin 43 is brought into contactwith another coil lock member 40 so as not to rotate any more.

According to the present invention, as described above, it is possibleto control the rotation of the guide sheath around its axis which is acause of the looseness within a limit, so that no relative loosenessbetween the guide sheath and operating wire due to shrinkage of the coilsheath can be caused.

As a result, a play and reduction of a bending angle are practicallyinsignificant and it is possible to retain a good insertability andperformance of observation and treatment of an endoscope for a prolongedtime. In addition, because of no looseness, the use of an endoscope isnot interrupted and the expense for repairing is not increased.

Experimental results confirming the effects described above are shown asfollows.

With an endoscope for the colon, a life tolerance test is conducted tothe guide sheaths controlled and not controlled in rotation around itsaxis to measure a play and reduction of a bending angle.

                  TABLE 1                                                         ______________________________________                                                      Reduction of a                                                                bending angle                                                                           Play                                                  ______________________________________                                        One controlled  25°  50°                                        in rotation                                                                   One not cont-   45°  75°                                        rolled in                                                                     rotation                                                                      ______________________________________                                    

As shown in Table 1, a play and reduction of a bending angle can be soreduced by controlling the rotation of the guide sheath that there ispractically no problem.

What is claimed is:
 1. A bending device for an endoscope including:acoil sheath housed within the insertable portion thereof and anoperating wire inserted in said coil sheath for connecting a bendableportion on the distal end side of said insertable portion and a bendingoperating portion on the proximal end side of the endoscope,characterized by: fixing means for fixing the distal end of said coilsheath on the bendable portion side so as not to rotate around its axis;and a coil lock member secured to the proximal end of the coil sheath atthe operating side; and a coil lock holder disposed at the operatingside and having an engagement portion which engages with said coil lockmember to prevent the coil lock member from rotating around its axis. 2.A bending device according to claim 1 in which:said coil lock member isin a insubstantially cylindrical form with a pair of cut portionsprovided in the middle of the outer periphery thereof so as to haverespective planes in parallel to each other at symmetrical positionsshifted by 180°, in which the proximal end of the coil sheath is fixedafter being inserted on the center axis of the coil lock member, saidcoil lock holder being formed by a plate member and being provided witha horizontal slit for receiving said cut portion, thereby preventingsaid coil sheath from rotating by fitting said coil lock member in saidcoil lock holder.
 3. A bending device according to claim 1 in which:saidcoil lock member is in a substantially cylindrical form with a pair ofcut portions provided in the middle of the outer periphery thereof so asto have respective planes in parallel to each other at symmetricalpositions shifted by 180°, in which the proximal end of the coil sheathis fixed after being inserted on the center axis of the coil lockmember, said coil lock holder being formed by a plate member and beingprovided with a vertical slit for receiving said cut portion, therebypreventing said coil sheath from rotating by fitting said coil lockmember in said coil lock holder.
 4. A bending device according to claim1 in which:said coil lock member is in a substantially cylindrical formwith a hole provided in the middle of the outer periphery thereof, inwhich the proximal end of the coil sheath is fixed after being insertedon the center axis of the coil lock member, said coil lock holder beingformed by a plate member in which a slit is provided for inserting saidcoil lock member therein, thereby preventing said coil sheath fromrotating by inserting a set screw passing through said coil lock memberin said hole after said coil lock member is fitted in said coil lockholder.
 5. A bending device according to claim 1 in which:said coil lockmember is in a substantially rectangular parallelepiped form providedwith a groove on the one vertical side thereof and said coil lock holderbeing formed by a plate member provided with a horizontal slit, therebypreventing said coil sheath from rotating by inserting said coil lockmember in said horizontal slit so as to engagingly fit said groove withsaid horizontal slit.
 6. A bending device according to claim 1 in whichsaid coil lock member into which said coil sheath is inserted andsecured thereto is inserted into said coil lock holder and is fixedthereto by an adhesion process for preventing said coil sheath fromrotating.